1. Field of the Invention
The invention relates to a touch control device comprising a plate capable of receiving an applied force, at least one slit which surrounds a partly cut-out portion in the plate while retaining a connection area with a remaining portion of the plate, and strain gauge detectors for supplying measurement signals which are a measure of deformations of the plate.
Such a device is used for supplying commands to a command reception unit.
The invention also relates to a keyboard in which a plurality of touch control devices are used.
2. Background of the Invention
U.S. Pat. No. 4,550,384 describes a device which supplies the coordinates of a point of application of a force on a surface. To achieve this, the surface is provided with four straight slits arranged in four corners of a plate, which slits cut through the plate parallel to each side, thus leaving tongues. The latter may alternatively be arranged towards the centres of the sides of the plate.
The plate is mounted on a frame and the cut-out ends of the tongues are fixedly connected with the frame. The point of application of the force is then formed by the portion of the plate outside the tongues. The tongues are provided with strain gauges.
The coordinates of the point of application of the force which calls up the deformations of the tongues can be calculated from the measurement signals supplied by the assembly of strain gauges.
Such a device is adapted to the calculation of the coordinates of a point of application and renders it possible to process measurement signals issued by several strain gauges suitably distributed over the surface of the plate collectively, without taking into account the intensity of the applied force. The point of application only is considered.